My first attack on problem situations such as this is to treat with M power, agitated and left to dwell for 20 mins., then extract. Then you can deal with any problem still there. I recently had to clean a white man made, 15 years old, never been cleaned, 3 dogs, "just do the best job you can mate, I'm not expecting miracles." This carpet had stains on it's stains and I told him to replace it. "Just do your best mate" he said. I sprayed 3 litres of M power solution at 120 to 1, worked it in with a Scrubba de luxe from Extracta, sprayed more in front of the settee and scrubbed, sprayed even more and scrubbed even more, then I proceeded to set up my extraction operation which took me 5 mins. "hey that carpet's like new" custy offered, and stap me vitals, he was not far wrong. I left it another 15 mins and extracted slowly and deeply, then I rang the pope to register it as a 100% miracle, and we all lived happily ever after
Mike